During rolling, the horizontal rolls of a section rolling mill stand may shift laterally from their correct position under the effect of the load. It therefore becomes necessary to be able to correct the lateral position of the horizontal rolls.
According to the state of the art, the rolling efforts in the radial direction are taken up on each side of each horizontal roll by radial bearings mounted on the neck of the roll and housed in chocks. The efforts in the axial direction are taken up on one side of each roll by an axial thrust-bearing mounted by its inner ring on a reduced neck in the vicinity of the first neck in a thrust casing fixed on the chock or on the columns of the stand.
The inner race of the axial thrust-bearing is blocked on the roll on one side by a shoulder and on the other side near the end of the neck by a spacer ring. The spacer ring is blocked by a screw-nut assembly retained by a circular groove made in the neck at its end.
The outer race of the axial thrust-bearing is fixed in a sleeve comprising a thread on its outer envelope screwing into the inner bore of the thrust casing.
A first shafted pinion, which is moved manually or by a motor, meshes with a pinion keyed on the sleeve so that the latter screws into the thrust casing and moves the roll with respect to pinion keyed on the sleeve.
A second shaft pinion (moved like the first), meshes with a second pinion which is internally threaded and screws on the sleeve thereby enabling the system to be blocked in the position desired for the roll by making up the clearances.
According to the known method for axially adjusting the horizontal rolls, it is necessary for each adjustment to perform three successive acts on the two shafted control pinions:
First unlocking the system with the blocking pinion-nut, second displacing the roll by the desired amount with the adjusting pinion and third, locking the system with the locking pinion-nut.
A drawback presented by the adjustment method known in the art is that the sleeve may be accidentally rotated by the axial thrust bearing when the latter develops greater than that of locking, by virtue of overload, friction, etc. Furthermore, control of the displacement is not guaranteed because of difficulty in measuring.
It is an object of the present invention to propose an improved device for the accurate, stable and controlled movement and axial adjustment of the position of a roll by actuating each time one shafted pinion only.
To this end, according to the invention, the improved device is mounted in a casing fixed on an element of the stand and which comprises an envelope in which a sleeve fast with the outer race of the thrust-bearing is mounted for axial slide, a mechanism being provided to adjust the position of the sleeve with respect to the envelope of the casing which offers easy handling and a good resistance to thrust. [The adjusting mechanism incorporates screws.]
The sleeve is blocked in rotation in the envelope of the casing, and the adjusting mechanism comprises: a thread on the outer part of the sleeve on which are screwed two pinion-nuts; two end stops formed on the casing; two shafted pinions rotating in the casing each contiguous to a stop and meshing with a respective pinion-nut.
The two pinion-nuts are provided on their opposite face with a dog-clutch operated by rotation of one or the other for an approach of the pinion-nuts less than the difference between the distance between the stops and the sum of the widths of the pinions. It is thus possible to act on one shafted pinion in order to unlock the position of the roll, to adjust it and lock it again as will be seen hereinbelow. Moreover, the sleeve can no longer be rotated accidentally since it is sliding and locked in rotation by a key.
The shafted pinions are advantageously controlled by motors with reversible rotation.
These motors may advantageously be used as pulse counters and the adjustment underway may be controlled precisely.
The invention finds particularly advantageous application in a bearing surface arrangement in which said bearing is an axial thrust-bearing. A second bearing is provided, mounted in the chock housed in the columns and exclusively taking up the radial loads supported by the roll.
The casing may be fixed on the chock.